• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.284-284
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• 2015

본 연구는 퍼클로레이트의 생물학적 환원 과정에 있어서 고농도의 염이 미생물에게 어떤 영향을 미치는지를 다양한 방법을 통해서 알아보고 적절한 모델링 접근을 통하여 최적 환원속도를 위한 반응조 조건 및 설계에 필요한 요소들을 도출하기 위해 수행되었다. 100mL 합성폐수를 포함하는 플라스크를 이용한 실험이 수행되었고, 일정 농도의 퍼클로레이트와 유일 탄소원으로 아세트산나트륨이 사용되었다. 염화나트륨 농도가 $7490{\mu}s/cm$에서 $23700{\mu}s/cm$까지 증가하는 동안 퍼클로레이트의 생물학적 환원 속도는 현저하게 감소하였으며, $32100{\mu}s/cm$ 이상의 염화나트륨 농도에서는 퍼클로레이트가 환원되지 않았다. 동일한 농도의 염화나트륨, 염화암모늄, 염산 및 황산이 포함된 하수에서는 퍼클로레이트의 환원속도가 모두 비슷하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.277-277
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• 2015

본 연구는 퍼클로레이트의 생물학적 환원 과정에 있어서 나이트레이트의 존재가 미생물에게 어떤 영향을 미치는지를 실험을 통해서 알아보고 적절한 모델링 접근을 통하여 나이트레이트의 퍼클로레이트 환원에 대한 저해의 정량적 분석을 위한 요소들을 도출하기 위해 수행되었다. 100mL 합성폐수를 포함하는 플라스크를 이용한 실험이 수행되었고, 유일 탄소원으로 아세트산나트륨이 사용되었고, 전자수용체로는 퍼클로레이트와 나이트레이트가 사용되었다. 먼저 퍼클로레이트와 나이트레이트 각각을 단일전자수용체로서 넣은 실험을 진행하였다. 퍼클로레이트의 동역학계수 qmax, Ks, Y, b값은 각각 0.9(mgClO4-/mgMLSSday), 42.28(mgClO4-/L), 0.382(mgClO4-/mgMLSS), 0.05(day-1)로 계산되었다. 그리고 나이트레이트의 동역학 계수 qmax, Ks, Y, b값은 각각 13.81(mgNO3-/mgMLSSday), 239.78(mgNO3-/L), 0.275(mgNO3-/mgMLSS), 0.05(day-1)로 계산되었다. 나이트레이트와 퍼클로레이트를 동시에 넣었을 경우에는 나이트레이트의 동역학 계수는 qmax, Ks, Y, b 값은 각각 13.72(mgClO4-/mgMLSSday), 235.64(mgClO4-/L), 0.263(mgClO4-/mgMLSS), 0.05(day-1)로 큰차이 없었으나, 퍼클로레이트의 경우에는 qmax, Ks, Y, b값은 각각 0.6(mgClO4-/ mgMLSSday), 42.24(mgClO4-/L), 0.393(mgClO4-/mgMLSS), 0.05(day-1)로 qmax값은 감소하였고, Y값은 증가하는 모습을 보임으로써, 나이트레이트의 존재가 퍼클로레이트의 환원을 저해시키는 것을 확인할 수 있었다.

• Journal of Life Science
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• v.21 no.10
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• pp.1473-1480
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• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Microbial removal of perchlorate is the method of choice since microorganisms can reduce perchlorate into harmless end-products. Such microorganisms require an electron donor to reduce perchlorate. Conventional perchlorate-removal techniques employ heterotrophic perchlorate-reducing bacteria that use organic compounds as electron donors to reduce perchlorate. Since continuous removal of perchlorate requires a continuous supply of organic compounds, heterotrophic perchlorate removal is an expensive process. Feasibility of autotrophic perchlorate-removal using elemental sulfur granules and activated sludge was examined in this study. Granular sulfur is relatively inexpensive and activated sludge is easily available from wastewater treatment plants. Batch tests showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of granular sulfur as an electron donor. Perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as the perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of sulfur particles were used for the autotrophic perchlorate-removal, suggesting that sulfur particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of the biofilm sample obtained from enrichment culture that used sulfur particles for $ClO_4^-$-degradation.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.29-34
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• 2009

In this study, a chloride ion probe as a direct measurement for perchlorate reduction was used to determine whether biological perchlorate reduction was inhibited by other electron acceptors ($O_2$ and ${NO_3}^-$) and to investigate competition of electron acceptors for using electron donors. Profiles of chloride production (= perchlorate reduction) in flasks containing perchlorate reducing populations were monitored by a chloride ion probe. Biological reduction of 2 mM perchlorate was inhibited by 2 mM nitrate that chloride production rate was decreased by 30% compared to perchlorate used as the only electron acceptor and chloride production rate was decreased by 70% when acetate was limited. Reduction of 2mM perchlorate was completely inhibited by oxygen at 7~8 mg/L, regardless of acetate excess / limitation.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.675-680
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• 2013

This research was done to evaluate the potential for destruction of perchlorate in municipal sewage. Laboratory experiments were conducted in flasks containing 3 liters of raw sewage. Sewage was mixed with defined amount of perchlorate and various additives. Perchlorate reduction in sewage did occur, but was quite variable, ranging from 0 to 72% over 72 hour. Addition of even a small amount of perchlorate acclimated biomass (167 mg/L SS) significantly reduced the lag and resulted in complete perchlorate removal. Perchlorate reduction in sewage-brine mixtures was inhibited when the dissolved oxygen level was greater than 2 mg/L, and when the mixture salinity was relatively high (conductivity = 14 mS with equivalent TDS = 8 g/L). When nitrate ($NO_3{^-}$) was present with perchlorate in the laboratory flask tests of sewage-brine mixtures, nitrate reduction proceeded first. A significant amount of nitrite ($NO_2{^-}$) accumulated in the sewage-brine mixtures, accounting for about 66% of initial nitrate nitrogen ($NO_3$-N).

• Journal of Korean Society of Environmental Engineers
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• v.36 no.5
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• pp.352-358
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• 2014

The feasibility of perchlorate reducing-bacteria isolated from the sludge of an anaerobic digester was determined using ammonium perchlorate in aqueous medium. Growth kinetics of the two perchlorate reducing bacteria including Rhodococcus sp. YSPW01 and YSPW02 were investigated using acetate as the electron donor in batch experiment. The growth of YSPW01 and YSPW02 reached a steady-state at 26 and 9 h, respectively. The initial perchlorate concentration was completely reduced within 8 and 7 h by YSPW01 and YSPW02, respectively. The reduction rates were 2.1 and $15mg\;L^{-1}h^{-1}$ for YSPW01, and 3.2 and $15.5mg\;L^{-1}h^{-1}$ for YSPW02, at 1:1 and 5:1 ratios of acetate:perchlorate (w:w), respectively. In this study, the bacteria Rhodococcus sp. YSPW01 and YSPW02 demonstrated a potential for the perchlorate reduction, which could be further investigated for development of an efficient strategy to treat the perchlorate contaminated waters.

• Journal of Life Science
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• v.21 no.3
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• pp.444-450
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• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Autotrophic perchlorate-reducing bacteria (PRB) use hydrogen gas ($H_2$) as an electron donor to remove perchlorate. Since iron corrosion can produce $H_2$, feasibility of autotrophic perchlorate-removal using zero-valent iron (ZVI) was examined in this study using activated sludge that is easily available from a wastewater treatment plant. Batch test showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of ZVI. The perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of iron particles used for the autotrophic perchlorate-removal, suggesting that iron particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of biofilm sample obtained from the ZVI-added enrichment culture used for $ClO_4^-$-degradation. A major band of the biofilm sample was most closely related to the class Clostridia.

• Journal of Life Science
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• v.23 no.5
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• pp.676-681
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• 2013

Perchlorate (${ClO_4}^-$) is an emerging contaminant found in surface water and soil/groundwater. Microbial removal of perchlorate is the method of choice since perchlorate-reducing bacteria (PRB) can reduce perchlorate to harmless end-products. A previous study [3] showed experimental evidence of autotrophic perchlorate removal using elemental sulfur granules and activated sludge. The granular sulfur is a relatively inexpensive electron donor, and activated sludge is easily available from a wastewater treatment plant. A batch test was performed in this study to further investigate the effect of various environmental parameters on the perchlorate degradation by sludge microorganisms when elemental sulfur was used as electron donor. Results of the batch test suggest optimum conditions for autotrophic perchlorate degradation by sludge microorganisms. The results also show that sulfur-oxidizing PRB enriched from activated sludge removed perchlorate better than activated sludge. Taken together, this study suggests that autotrophic perchlorate removal using elemental sulfur and activated sludge can be improved by employing optimized environmental conditions and enrichment culture.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.92-97
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• 2014

Perchlorate ($ClO_4^-$) is an emerging contaminant of soil/groundwater and surface water. $ClO_4^-$ has been shown to inhibit iodide uptake into the thyroid gland and cause a reduction in thyroid hormone production. $ClO_4^-$ is highly soluble and very stable in water. Biodegradation by $ClO_4^-$-reducing bacteria (PRB) is considered the most important factor in natural attenuation of $ClO_4^-$. Rivers in an industrial complex have potential to be contaminated with $ClO_4^-$ discharged from point or non-point sources. In this study, water samples were taken from the rivers running through the Gumi industrial complexes and used for batch test to analyze $ClO_4^-$-degradation potential of river microorganisms. The results of 83-h batch culture showed that $ClO_4^-$-removal efficiency of all samples was 0.77% or less without addition of an external electron ($e^-$) donor. However $ClO_4^-$-removal efficiency was higher when an $e^-$ donor (acetate, thiosulfate, $S^0$, or $F^0$) was added into the batch culture, showing up to 100% removal efficiency. The removal efficiency was various depending on type of $e^-$ donor and site of sampling. When acetate was used as an $e^-$ donor, the highest $ClO_4^-$-removal efficiency was observed among the $e^-$ donors used in this study, suggesting that activity of heterotrophic PRB was dominant. The results of this study provide basic information on natural attenuation of $ClO_4^-$ by river microorganisms. The information can be useful to prepare a strategy to enhance efficiency of $ClO_4^-$ biodegradation for in situ bioremediation.